Guide device, coolant duct and diffusion vacuum pump

ABSTRACT

A guide device for a diffusion vacuum pump having a plurality of annular guide plates. The guide plates being arranged radially, wherein at least one guide plate has a first section starting from a connection point and a second section starting from the connection point. Therein, the first section extends axially in a first direction, the second section extending axially in the opposite second direction. Therein the first section is designed to taper radially and/or the second section is designed to taper radially.

CROSS-REFERENCE OF RELATED APPLICATION

This application is a Section 371 National Stage Application of International Application No. PCT/EP2021/073452, filed Aug. 25, 2021, which is incorporated by reference in its entirety and published as WO 2022/043358 A3 on Mar. 3, 2022, the content of which is hereby incorporated by reference in its entirety and which claims priority of German Application No. 20 2020 104 944.5, filed Aug. 26, 2020.

BACKGROUND

The present invention relates to a guide device for a diffusion vacuum pump, a coolant duct for a vacuum pump and a diffusion vacuum pump with such a guide device and coolant duct.

Known diffusion vacuum pumps have housings with an inlet and an outlet, wherein one or more nozzles are arranged in the housing. Furthermore, a heating element is provided by which a propellant, in particular an oil, is vaporized. This vaporized propellant exits through the nozzles. The propellant transports gas molecules from the vacuum in the direction of the outlet of the diffusion vacuum pump. The propellant condenses on the outer wall of the diffusion vacuum pump and thereby returns to a storage space in which the heating element is also provided. As a result, the propellant is in turn vaporized and a conveying circuit for the propellant is produced, so that a gaseous medium is conveyed from the inlet of the diffusion vacuum pump to the outlet of the diffusion vacuum pump.

A disadvantage of this process, however, is that oil molecules of the propellant can enter the receptacle connected to the inlet of the diffusion vacuum pump. This contaminates the vacuum in the receptacle and vacuum equipment can be damaged.

To prevent backstreaming of oil into the receptacle, it is known to provide vapor barriers on the inlet-side nozzle or the high vacuum-side nozzle of the diffusion vacuum pump. These vapor barriers have an additional condensation surface on which the propellant condenses and thus cannot enter the receptacle. However, this has the disadvantage that the conductance and thus the pump rate of the diffusion vacuum pump is significantly reduced. If the area of such a vapor barrier is small, in particular smaller than the inlet cross section of the diffusion vacuum pump, these vapor barriers are usually connected directly to the inlet-side nozzle. This complicates the structure in the area of the nozzle and makes cleaning the vapor barrier more difficult. If such vapor barriers are to be provided over the entire inlet surface or the entire inlet cross section, it is known to provide such vapor barriers as a separate vacuum element with a separate housing. The housing thus has a first flange for connection to the diffusion vacuum pump and a second flange for connection to the receptacle. This makes the structure unnecessarily large. In particular, when the vapor barrier is replaced, the available installation space must then be adapted.

Known vapor barriers are also operated at temperatures between 0 and −196° C. (liquid nitrogen). Due to the direct connection to the nozzle, this leads to an unwanted transfer of the cooling energy to the nozzle itself. Furthermore, in known solutions the supply of coolant is ensured by the housing of the diffusion vacuum pump itself. This results in a significant transfer of cold from the coolant to the housing of the diffusion vacuum pump. Moisture in the ambient air condenses on the outside of the diffusion vacuum pump and freezes and thus is deposited as a layer of ice.

The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to implementations that solve any or all disadvantages noted in the background.

SUMMARY

The object of the present invention is to create an integrated guide device for a diffusion vacuum pump which can be cooled in a simple manner and prevents the backstreaming of oil into the receptacle.

The object is achieved by the guide device according to claim 1, the coolant device according to claim 11 and the diffusion vacuum pump according to claim 13.

The guide device according to the invention for a diffusion vacuum pump has a plurality of annular guide plates, the guide plates being arranged radially with respect to one another. In this case, at least one guide plate has a first section starting from a connection point and a second section starting from the connection point. The first section extends axially in a first direction, the second section extending axially in the opposite direction or second direction. In the installed state, the first direction points in the direction of the receptacle or the inlet of the guide device and the second direction points in the direction of the diffusion vacuum pump. The first section is designed to taper radially. As an alternative or in addition to this, the second section is designed to taper radially. Thus, starting from the common connection point the radius changes along the axial direction and a condensation surface of one guide plate which is angled with respect to the condensation surface of the other guide plate is created by means of the first section and the second section. The enlarged, angled condensation surface formed by the first section and the second section efficiently prevents backstreaming of the oil molecules of the vaporized propellant.

All guide plates are preferably designed in the same way and thus preferably each guide plate has a first section and a second section which are designed to taper radially along the first and second axial directions. This efficiently prevents the backstreaming of oil molecules. At the same time, the individual guide plates can be spaced far apart from one another, so that the structure of the guide device is simplified and the guide device can be cleaned easily. At the same time, conductance of the guide device is increased without decreasing the barrier function.

An axial end point of the first section of one of the guide plates, of several or all of the guide plates, is preferably arranged radially above or radially further inward from the connection point of the immediately adjacent guide plate, in particular the radially inner, immediately adjacent guide plate. The axial end point of the first section is the axial end point of the guide plate in the first direction, which is opposite the connection point of the guide plate in question. The first section thus extends from the connection point to its axial end point. As an alternative or in addition to this, an axial end point of the second section of one of the guide plates, of several or all of the guide plates, is arranged radially above or radially further inward from the connection point of the immediately adjacent guide plate, in particular the radially inner, immediately adjacent guide plate. The axial end point of the second section is the axial end point of the guide plate in the second direction, which is opposite the connection point of the guide plate in question. The second section thus extends from the connection point to its axial end point. An optically tight guide device is thus created by this configuration. This means that it is not possible to look directly through the guide device, so that there is also no direct path through the guide device for oil molecules. Oil molecules thus pass through the guide device exclusively by contact with one of the condensation surfaces formed by the guide plates. Here, however, the oil molecules are condensed and thus do not enter the receptacle. In this way, backstreaming of the oil molecules can be completely or at least almost completely prevented.

Three to five guide plates are preferably provided, so that the number of guide plates covers the entire inlet or inlet cross section of the diffusion vacuum pump.

At least one guide plate, several or all guide plates is/are preferably connected to a cooling element, in particular designed as a coolant line, for cooling the guide plate. This allows the temperature of the guide plates to be reduced down to −196° C., so that efficient condensation of the propellant vapor on the guide plates is achieved.

The first section of the at least one cooled guide plate is preferably formed by a first guide plate element. The second section of the at least one cooled guide plate is also formed by a second guide plate element. The first guide plate element and the second guide plate element are connected to one another by means of the cooling element. Thus, there is only a connection between the first guide plate element and the cooling element, in particular designed as a coolant line. Likewise, there is also only a connection between the second guide plate element and the cooling element. In particular, there is no direct connection between the first guide plate element and the second guide plate element. This creates a particularly simple structure which is simple and inexpensive to manufacture.

Preferably, the first guide plate element and/or the second guide plate element of the at least one cooled guide plate has a substantially and preferably exclusively radially extending section for connection to the cooling element. This creates a large-area connection of the first guide plate element or the second guide plate element to the cooling element. Furthermore, the structure is simplified in order to achieve simple and inexpensive manufacture.

Preferably, the first guide plate element and/or the second guide plate element of at least one, more than one and preferably all guide plates comprise at their respective axial end a substantially and preferably exclusively axially extending section. This axially extending section increases stability of the individual first and/or second guide plate elements.

The axial length of the second section preferably decreases from an outer guide plate to an inner guide plate. Thus, a guide plate arranged radially further outward has a second section which extends further in the axial direction than a guide plate arranged radially further inward, in the direction of the nozzle. This ensures that the guide plates arranged radially further inward do not interfere with and thus adversely affect the jet of propellant which exits from the nozzle of the diffusion vacuum pump. At the same time, with the guide plates located further outward, it is ensured that a sufficient condensation surface is available to prevent the oil from streaming back.

The guide device preferably has precisely one flange in order to be connected to a diffusion vacuum pump. In particular, the guide device does not have a housing, but can be arranged within the housing of the diffusion vacuum pump by means of the one flange. A particularly space-saving structure is achieved in this way.

The guide plates are preferably connected to the flange in particular by means of webs, wherein the webs extend in particular radially. This ensures sufficient stability of the guide device. At the same time, the installation space of the guide device can be kept small.

The webs preferably have thermal decoupling elements, in particular made of plastics material. This ensures that the low temperature of the guide device is not transferred to the flange and thus to the vacuum pump. It is therefore possible to operate the guide device at particularly low temperatures of −196° C.

Furthermore, the present invention relates as an independent invention to a coolant duct for a vacuum pump, in particular a diffusion vacuum pump. The coolant duct has a flange, wherein the flange has an inwardly open recess and a coolant line is arranged in the recess. The recess has a first diameter and the coolant line has a second diameter, wherein the second diameter is smaller than the first diameter, so that the coolant line is guided in the recess without contact. Since there is a vacuum inside the flange, the contact-free guiding of the coolant line inside the flange ensures that no cold energy is transferred from the coolant in the coolant line to the flange. The coolant duct according to the invention thus ensures that the low temperatures of the coolant in the coolant line are not transferred to the outside of the vacuum pump via the flange, and ice formation on the outside of the vacuum pump is also reduced or prevented.

The coolant line is preferably connected to the flange on the outside of the flange. For example, the flange and the coolant line can be welded in order to create a vacuum tightness. A connection on the outside of the flange only creates a small cold bridge through which the cold energy is transferred from the cooling line to the flange. In particular, if the connection is made by means of welding, this connection does not extend, or only extends minimally, into the recess of the flange, so that the cold bridge can be kept small.

A sealing element, which is made in particular of plastics material, is preferably arranged at least partially between the coolant line and the flange. Here, plastics material has a significantly lower thermal conductivity than stainless steel or other metals, so that thermal insulation can be achieved between the coolant line and the flange. At the same time, the sealing element ensures that the coolant duct is vacuum-tight.

Furthermore, the present invention relates as an independent invention to a diffusion pump with at least one nozzle, wherein a propellant is conveyed through the nozzle in order to transport a gaseous medium from an inlet of the diffusion vacuum pump to an outlet. The diffusion vacuum pump has a guide device, as described above, which is arranged directly above the inlet-side nozzle, i.e. in the direction of the receptacle. If, for example, the diffusion pump has only one nozzle, the guide device is arranged directly above this one nozzle. However, if the diffusion vacuum pump has a plurality of nozzles, the guide device is arranged directly above the nozzle, which is arranged in the high vacuum area, i.e. furthest in the direction of the inlet of the diffusion vacuum pump or the receptacle.

The diffusion vacuum pump preferably has a coolant duct, as described above. The coolant duct is arranged in the flange of the guide device.

There is preferably no contact between the inlet-side nozzle and the guide device, so that a transfer of cold from the guide device to the inlet-side nozzle is prevented. The guide device is thus arranged in a thermally insulated manner within the vacuum pump, which ensures efficient cooling of the guide device and, at the same time, prevents the transfer of cold from the guide device to other parts of the diffusion vacuum pump.

The diffusion pump preferably has a connection flange, the flange of the guide device being connected to the connection flange of the diffusion vacuum pump. In particular, the guide device does not have its own housing, so that the guide device with the flange is connected directly to the connection flange of the vacuum pump and is thus arranged within the housing of the diffusion pump.

The guide device preferably covers the entire cross sectional area of the inlet of the diffusion vacuum pump.

The invention is explained in more detail below on the basis of a preferred embodiment with reference to the accompanying drawings.

The Summary is provided to introduce a selection of concepts in a simplified form that are further described in the Detail Description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

BRIEF DESCRIPTION OF TE DRAWINGS

In the drawings:

FIG. 1 is a perspective view of the guide device according to the present invention,

FIG. 2 is a sectional view of the guide device according to FIG. 1 ,

FIG. 3 is a view from above of the guide device according to FIG. 1 ,

FIG. 4 shows a diffusion vacuum pump according to the present invention and

FIG. 5 shows a coolant duct according to the present invention.

DETAILED DESCRIPTION

The guide device 10 according to the invention according to FIG. 1 has a flange 12 by means of which the guide device 10 can be connected to a diffusion vacuum pump 40. In this case, no components protrude beyond the upper side 14 of the flange 12. The components of the guide device 10 are thus arranged below the upper side 14 of the flange 12 and thus protrude into the housing 42 in the diffusion vacuum pump 40. In particular, the guide device 10 does not have its own housing. A particularly compact design is achieved in this way. And the diffusion vacuum pump 40 can thus be connected to a receptacle or a vacuum device by means of the flange 12 of the guide device.

In the example shown in the figures, the guide device 10 has four guide plates 16 which are arranged radially to one another. The guide plates 16 are connected to the flange 12 of the guide device 10 by means of radial webs 18. The radial webs 18 are only indirectly connected to the flange 12 via thermal insulation elements 20 for thermal separation between the flange 12 and the guide plates 16. A transfer of the cold energy from the guide plates 16 to the flange 12 is thus prevented.

It can be seen in FIG. 3 that the guide plates 16 have a first section 22 which extends from a common connection point 24 in a first direction 23 or in the direction of the inlet 26 of the guide device. The radius of the first section 22 is reduced starting from the common connection point 24, so that the first section 22 has a smaller radius at its axial end 28 than at the common connection point 24. Likewise, a second section 30 extends in the direction or second direction 31 opposite to the axial direction of extension of the first section 22 or first direction 23. The radius of the second section 30 also decreases starting from the common connection point 24, so that the second section 30 has a smaller radius at the axial end 32 than at the common connection point 24. The first section 22 and the second section 30 are only connected to one another at the common connection point 24. The first section 22 extends in the radial direction so that it lies above the common connection point 34 of the immediately adjacent guide plate 16. The second section 30 also extends so that the axial end 32 of the second section 30 lies radially below the common connection point 34 of the immediately adjacent guide plate 16. This creates an impermeable configuration of the guide device 10, so that oil molecules cannot pass directly through the guide device 10, but always strike a condensation surface and thus cannot enter the receptacle.

As can be seen on FIG. 3 , at the axial end 28, 32 of the first section 22 and/or the second section 30 the guide plates 16 comprise an axially extending section 33. By the axially extending section 33 mechanical stability of the individual guide plates is enhanced. Thus, damage of the guide plates 16 during assembly and disassembly is avoided.

As can be seen in FIG. 3 , the guide plates 16 located further inside have a smaller axial extent of the second section. This ensures that propellant vapor exiting through the nozzle 60 does not collide with the guide plates 16, but can instead be guided unhindered in the conveying direction.

Furthermore, the first section 22 is indirectly connected to the second section 30 via a cooling element 36, wherein the cooling element 36 is in particular a coolant line. Cooling energy is transferred to the guide plates 16 by means of the cooling element 36 in order to achieve effective condensation of the oil molecules on the condensation surfaces of the guide plates 16. The cooling element 36 is connected to a coolant duct 50. Here, the flange 12 has a recess or depression 52 which is open to the inside. The recess 52 has a first diameter D1. Furthermore, the coolant line 36 has a second diameter D2, wherein the second diameter D2 is smaller than the first diameter D1, so that the coolant line 36 is at least partially guided within the flange 12 without contact. Furthermore, the coolant line 36 is connected to the outside of the flange 12, so that a vacuum-tight connection is created between the coolant line 36 and the flange 12. For example, the coolant line 36 can be connected to the outside of the flange 12 by welding. In this case, the coolant line is guided over the greater part within the recess 52 of the flange 12 without contact and a cold bridge is created only in the area of the weld seam 54. However, this cold bridge has a small cross section, so that a transfer of the cold energy from the coolant line 36 to the flange 12 is reduced. As an alternative or in addition to this, a sealing element (not shown) can be provided at least partially, which is arranged between the flange 12 and the coolant line 36, in particular within the depression or recess 52 of the flange 12. The sealing element consists in particular of plastics material and thus has a lower thermal conductivity than stainless steel or another metal from which the flange 12 is made. The cold energy which is transmitted from the coolant line 36 to the flange 12 is thus reduced. This is because there is a vacuum in the region of the recess 52 and therefore heat transfer does not take place, or only takes place to a small extent, in this region. Of course, the guide device 10 has more than one coolant duct. For example, according to FIG. 2 , an inlet 60 and a return 62 for the coolant can be provided, wherein both the inlet 60 and the return 62 are formed as described above and shown in FIG. 5 .

FIG. 4 shows a diffusion vacuum pump according to the present invention. This has a housing 42 and an outlet 41. Furthermore, an inlet 43 of the diffusion vacuum pump 40 is provided and is formed by a flange 44. The flange 12 of the guide device 10 is connected to the flange 44 of the diffusion vacuum pump 40, so that the guide device is arranged completely within the housing 42 of the diffusion vacuum pump 40. Furthermore, the inlet 26 of the guide device 10 forms the inlet of the diffusion vacuum pump 40.

The diffusion vacuum pump 40 has a storage space 45 for storing a propellant. A heating element is provided in the storage space 45, by means of which the propellant is vaporized and exits again through the nozzles 46. In the process, gas molecules are carried away from the vacuum and conveyed in the direction of the outlet 41. The propellant condenses on the inner walls 47 of the housing 42 and thus returns to the storage space 45.

The guide device 10 is arranged above the inlet-side nozzle 46, i.e. from the inlet-side nozzle 46 in the direction of the receptacle. There is no contact between the inlet-side nozzle 46 and the guide device 10, so that the cold energy is not transferred from the guide device to the nozzle.

Thus, a guide device or vapor barrier is created that is integrated into the housing of the diffusion vacuum pump, is nevertheless easy to install and remove again and is completely impermeable. Furthermore, due to the coolant duct according to the invention, it is possible to cool the guide device, even at very low temperatures of down to −196° C., without this having a negative effect on the functionality of the diffusion pump.

Although elements have been shown or described as separate embodiments above, portions of each embodiment may be combined with all or part of other embodiments described above.

Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are described as example forms of implementing the claims. 

1. A guide device for a diffusion vacuum pump having a plurality of annular guide plates, the guide plates being arranged radially, wherein at least one guide plate has a first section starting from a connection point and a second section starting from the connection point, wherein the first section extends axially in a first direction, the second section extending axially in the opposite second direction, wherein the first section is designed to taper radially and/or wherein the second section is designed to taper radially.
 2. The guide device according to claim 1, characterized in that all guide plates are designed in the same way.
 3. The guide device according to claim 1, characterized in that an axial end point of one of the guide plates is located radially above or further inside the connection point of the directly adjacent guide plate.
 4. The guide device according to claim 1, characterized in that 3 to 5 guide plates are provided.
 5. The guide device according to claim 1, characterized in that at least one guide plate is connected to a cooling element for cooling the guide plate.
 6. The guide device according to claim 5, characterized in that the first section and the second section of the at least one cooled guide plate are each formed by a first guide plate element and second guide plate element, wherein the first guide plate element and the second guide plate element are connected to one another by means of the cooling element.
 7. The guide device according to claim 6, characterized in that the first guide plate element and/or the second guide plate element of the at least one cooled guide plate have a substantially radially extending section for connection to the cooling element.
 8. The guide device according to claim 1, characterized in that the axial length of the second section decreases from an outer guide plate to an inner guide plate.
 9. The guide device according to claim 1, characterized in that the guide plates are connected to a flange by means of, in particular, radially extending webs.
 10. The guide device according to claim 9, characterized by a coolant duct for supplying the cooling element with a coolant wherein the coolant duct comprises a flange, the flange having a recess with a first diameter, wherein a coolant line is arranged in the recess, the coolant line having a second diameter, the second diameter being smaller than the first diameter so that the coolant line is guided in the recess without contact.
 11. A coolant duct for a vacuum pump, in particular a diffusion pump, with a flange, the flange having a recess with a first diameter, wherein a coolant line is arranged in the recess, the coolant line having a second diameter, the second diameter being smaller than the first diameter so that the coolant line is guided in the recess without contact.
 12. The coolant duct according to claim 11, characterized in that the coolant line is connected to the flange on the outside of the flange.
 13. A diffusion pump having at least one nozzle, wherein a guide device according to claim 1 is arranged directly above the inlet-side nozzle.
 14. The diffusion pump according to claim 13, characterized by a coolant duct wherein the coolant duct comprises a flange, the flange having a recess with a first diameter, wherein a coolant line is arranged in the recess, the coolant line having a second diameter, the second diameter being smaller than the first diameter so that the coolant line is guided in the recess without contact.
 15. The diffusion vacuum pump according to claim 13, characterized in that there is no contact between the nozzle on the inlet side and the guide device.
 16. The diffusion pump according to claim 13, characterized by a connection flange, wherein the flange of the guide device is connected to the connection flange. 